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Big Ip Access Policy ManagerApplication · F5

CVE-2020-5877

HIGH · 7.5 CVSS v3.1 Published 2020-04-30
Fix available
A fix is available. Upgrade to after 15.1.0.1 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
On BIG-IP 15.0.0-15.1.0.1, 14.1.0-14.1.2.3, 13.1.0-13.1.3.3, 12.1.0-12.1.5.1, and 11.6.1-11.6.5.1, malformed input to the DATAGRAM::tcp iRules command within a FLOW_INIT event may lead to a denial of service.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A denial-of-service vulnerability exists in F5 BIG-IP where malformed input to the DATAGRAM::tcp iRules command within a FLOW_INIT event can cause the system to become unavailable. This affects the iRules (Tcl-based traffic management scripting) component used for traffic manipulation.

MitigationApply the applicable F5 BIG-IP software update for the affected versions (15.1.0.2+, 14.1.2.4+, 13.1.3.4+, 12.1.5.2+, 11.6.5.2+). Until patched, restrict management access to trusted networks and review iRules for any unnecessary or vulnerable configurations.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Big Ip Access Policy ManagerApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1
Big Ip Advanced Firewall ManagerApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1
Big Ip AnalyticsApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1
Big Ip Application Acceleration ManagerApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1
Big Ip Application Security ManagerApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1
Big Ip Domain Name SystemApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1
Big Ip Fraud Protection ServiceApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1
Big Ip Global Traffic ManagerApplication
Affected:>= 11.6.1, <= 11.6.5.1>= 12.1.0, <= 12.1.5.1>= 13.1.0, <= 13.1.3.3>= 14.1.0, <= 14.1.2.3>= 15.0.0, <= 15.1.0.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed BIG-IP version
    Run 'tmsh show sys version' in the TMSH CLI or check System > Software Management > Software Images in the web interface
    Affected if The version falls within 11.6.1-11.6.5.1, 12.1.0-12.1.5.1, 13.1.0-13.1.3.3, 14.1.0-14.1.2.3, or 15.0.0-15.1.0.1
  2. Determine if iRules are configured
    Run 'tmsh list ltm rule' to list all deployed iRules, or check Local Traffic > iRules in the web interface
    Affected if No iRules are deployed (not affected); if iRules exist, proceed to next check
  3. Search for DATAGRAM::tcp usage in iRules
    Run 'tmsh list ltm rule all-properties' and search for the string 'DATAGRAM::tcp' within the rule definitions
    Affected if Any iRule contains the DATAGRAM::tcp command and the system is in an affected version range
  4. Check for FLOW_INIT event handler in affected iRules
    In the iRules containing DATAGRAM::tcp, verify if they reference the FLOW_INIT event (e.g., 'when FLOW_INIT { ... }')
    Affected if An iRule uses DATAGRAM::tcp within a FLOW_INIT event handler and the version is in the affected range

The environment is affected if BIG-IP is running a version within the listed ranges AND an iRule containing the DATAGRAM::tcp command is deployed in a FLOW_INIT event handler.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to a release after 15.1.0.1
Interim mitigation

Apply the applicable F5 BIG-IP software update for the affected versions (15.1.0.2+, 14.1.2.4+, 13.1.3.4+, 12.1.5.2+, 11.6.5.2+). Until patched, restrict management access to trusted networks and review iRules for any unnecessary or vulnerable configurations.

Fix this in Big Ip Access Policy Manager Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,648.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-5877 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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